Rust rings are a pain to remove. Prevent them by applying clear nail polish to the bottom of the metal container for a quick fix. Just be sure to let them dry properly. Oh, and try white vinegar for rust stains!
In addition to first aid staples, buy travel-size deodorant, lip balm, toothpaste, body lotion, mascara, lip gloss, or any other essential you may need. Throw everything in a small makeup bag and keep it in the glove box.